Mechanism for ssb transmission in nr-u

ABSTRACT

The present application is directed to an apparatus including a non-transitory memory including instructions stored thereon for monitoring synchronous signals and physical broadcast channels (SSBs) from a network node. The apparatus also includes a processor, operably coupled to the non-transitory memory, configured to execute a set of instructions. The instructions include configuring the apparatus for a STTC (SSB Transmission Timing Configuration). The STTC is a time interval with plural locations accommodating transmission of the SSBs. The instructions also include monitoring the STTC for the SSBs. The instructions further include determining a first one of the SSBs in a first slot of a subframe in a scheduled SSB transmission in the STTC has been transmitted at a first scheduled location, where the transmission of the first one of the SSBs is based upon confirmation of a successful Listen Before Talk (LBT) available channel prior to the scheduled SSB transmission in the STTC.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the National Stage of International Application No.PCT/US2019/031545, filed May 9, 2019 which claims the benefit ofpriority of U.S. Provisional application no. 62/669,613 filed May 20,2018, the contents of which is incorporated by reference in its entiretyherein.

FIELD

The present application is directed to mechanisms for synchronous signaland physical broadcast channel (SSB) transmission in new radiounlicensed (NR-U).

BACKGROUND

In NR, the SSB carries the essential signal and information such as theprimary synchronization signal (PSS), secondary synchronization signal(SSS) and Physical Broadcast Channel (PBCH). These are used by a UE toget synchronization and Master Information Block (MIB) in both theinitial cell search and connected state. If a UE cannot detect the SSB,the UE will have critical issues and will not be able to function in theNR system.

In NR-U, the gNB may not be able to transmit the SSB burst set on thepre-defined/configured location. This may be due to the LBT failure(channel is not available). This causes issues for UEs to detect SSB.

What is desired in the art are mechanisms to improve the reliability ofSSB transmission in NR-U.

SUMMARY

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to limit the scope of theclaimed subject matter. The foregoing needs are met, to a great extent,by the present application directed to mechanisms for SSB transmissionin NR-U.

One aspect of the application is directed to an apparatus including anon-transitory memory including instructions stored thereon formonitoring SSBs from a network node. The apparatus also includes aprocessor, operably coupled to the non-transitory memory, configured toexecute a set of instructions. The instructions include configuring theapparatus for a SSB Transmission Timing Configuration (STTC). The STTCis a time interval with plural locations accommodating transmission ofthe SSBs. The instructions also include monitoring the STTC for theSSBs. The instructions further include determining a first one of theSSBs in a first slot of a subframe in a scheduled SSB transmission inthe STTC has been transmitted at a first scheduled location, where thetransmission of the first one of the SSBs is based upon confirmation ofa successful Listen Before Talk (LBT) available channel prior to thescheduled SSB transmission in the STTC.

Another aspect of the application is directed to an apparatus includinga non-transitory memory including instructions stored thereon fortransmitting SSBs. The apparatus also includes a processor, operablycoupled to the non-transitory memory, configured to execute a set ofinstructions. The STTC is a time interval with plural locationsaccommodating transmission of the SSBs. The instructions includeperforming a LBT check on a channel. The instructions also includedetermining, based on the LBT check, availability of the channel, wherethe availability is established in a first slot of a subframe prior to ascheduled SSB transmission in the STTC at a first scheduled location.The instructions further include transmitting a first one of the SSBs inthe first slot during the scheduled SSB transmission in the STTC at thefirst scheduled location.

There has thus been outlined, rather broadly, certain embodiments of theinvention in order that the detailed description thereof may be betterunderstood, and in order that the present contribution to the art may bebetter appreciated.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to facilitate a more robust understanding of the application,reference is now made to the accompanying drawings, in which likeelements are referenced with like numerals. These drawings should not beconstrued to limit the application and are intended only to beillustrative.

FIG. 1A illustrates an exemplary communications system according to anembodiment of the application.

FIG. 1B illustrates an exemplary apparatus configured for wirelesscommunication according to an embodiment of the application.

FIG. 1C illustrates a system diagram of a radio access network and acore network according to an embodiment of the application.

FIG. 1D illustrates a system diagram of a radio access network and acore network according to another embodiment of the application.

FIG. 1E illustrates a system diagram of a radio access network and acore network according to yet another embodiment of the application.

FIG. 1F illustrates a block diagram of an exemplary computing system incommunication with one or more networks previously shown in FIGS. 1A,1C, 1D and 1E according to an embodiment of the application.

FIGS. 2A-2D illustrate LAA deployment scenarios.

FIGS. 3A-B illustrate SSBs transmitted by SSB burst subsets in NR-U.

FIG. 4 illustrates a STTC according to an aspect of the application.

FIG. 5 illustrates a bundled SSB transmission at thepre-defined/configured location according to an aspect of theapplication.

FIG. 6 illustrates a bundled SSB transmission with sliding within STTCaccording to an aspect of the application.

FIG. 7 illustrates a reservation signal assisted bundled SSBtransmission with sliding within STTC according to an aspect of theapplication.

FIG. 8 illustrates bundled SSB transmission with one SSB location slidewithin STTC according to an aspect of the application.

FIG. 9 illustrates SSB transmission with repetition in the frequencydomain according to an aspect of the application.

FIG. 10 illustrates RMSI CORESET FDM-ed with SSB in the same slotaccording to an aspect of the application.

FIG. 11 illustrates RMSI CORESET TDM-ed and FDM-ed with SSB in the sameslot according to an aspect of the application.

FIG. 12 illustrates a procedure for monitoring and receiving bundled SSBtransmissions in NR-U according to an aspect of the application.

FIG. 13 illustrates unbundled SSB transmission according to an aspect ofthe application.

FIG. 14 illustrates unbundled SSB transmission with opportunistictransmission within STTC according to an aspect of the application.

FIG. 15 illustrates unbundled SSB transmission with configuredopportunistic transmission according to an aspect of the application.

FIG. 16 illustrates unbundled SSB transmission with STTC and configuredopportunistic transmission according to an aspect of the application.

FIG. 17 illustrates a procedure for monitoring and receiving SSBtransmission with opportunistic transmission in NR-U according to anaspect of the application.

FIG. 18 illustrates SSB transmission with dedicated STTC according to anaspect of the application.

FIG. 19 illustrates procedures for monitoring and receiving thededicated SSB transmission with STTC according to an aspect of theapplication.

FIG. 20 illustrates SSB transmission with flexible index order accordingto an aspect of the application.

FIG. 21 illustrates procedures for monitoring and receiving the SSBtransmission with flexible index order according to an aspect of theapplication.

FIGS. 22A-C illustrate impacts of SSB shifting on RACH resourcesaccording to an aspect of the application.

FIG. 23 illustrates an impact of SSB shifting on FDM-ed resourcesaccording to an aspect of the application.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

A detailed description of the illustrative embodiments will be discussedin reference to various figures, embodiments and aspects herein.Although this description provides detailed examples of possibleimplementations, it should be understood that the details are intendedto be examples and thus do not limit the scope of the application.

Reference in this specification to “one embodiment,” “an embodiment,”“one or more embodiments,” “an aspect” or the like means that aparticular feature, structure, or characteristic described in connectionwith the embodiment is included in at least one embodiment of thedisclosure. Moreover, the term “embodiment” in various places in thespecification is not necessarily referring to the same embodiment. Thatis, various features are described which may be exhibited by someembodiments and not by the other.

According to one aspect of the application, mechanisms and proceduresfor a gNB to transmit the SSB in NR-U are envisaged. In another aspectof the application, mechanisms and procedures for a UE to detect the SSBin NR-U are envisaged. In an embodiment, several SSB transmissions maybe bundled together. If the bundle cannot be transmitted at theconfigured location due to LBT failure, it may be shifted within aconfigured transmission window.

In another embodiment, beam-based LBT may be performed for each SSB. TheSSBs with a successful LBT will be transmitted. For the failed LBTs, thegNB may perform another round(s) of LBT to determine whether theassociated SSBs can be transmitted.

In yet another embodiment, SSB transmission may be performed insuccession, i.e., one by one. A window is applied for each SSB'stransmission to improve reliability.

In yet even another embodiment, the index order carried by SSB may beflexible. The SSB may be transmitted at any SSB location with successfulbeam base LBT within the SSB burst transmission.

It is further envisaged in this application the offset by which the SSBhas shifted can be indicated by the gNB to a UE with one of thefollowing exemplary schemes:

(i) by the payload of PBCH;

(ii) By the PBCH DMRS;

(iii) Jointly by the payload of PBCH and PBCH DMRS;

(iv) By the spreading code; and

(v) By RMSI.

Definitions and Acronyms

Provided below are definitions for terms and phrases commonly used inthis application in Table 1.

TABLE 1 Acronym Term or Phrase BWP Bandwidth Part CA Carrier AggregationCE Control Element CORESET Control Resource Set C-RNTI CellRadio-Network Temporary Identifier CSI-RS Channel State InformationReference Signal DC Duel Connectivity DL Downlink DL-SCH Downlink SharedChannel eMBB enhanced Mobile Broadband FDD Frequency-Division Duplex FFSFor Further Study gNB NR NodeB HARQ Hybrid Automatic Repeat Request KPIKey Performance Indicators L1 Layer 1 L2 Layer 2 L3 Layer 3 LAA LicenseAssisted Access LTE Long Term Evolution MAC Medium Access Control MCGMaster Cell Group MIB Master Information Block MTC Machine TypeCommunication mMTC Massive Machine Type Communication NR New Radio OFDMOrthogonal Frequency Division Multiplexing PCell Primary Cell PHYPhysical Layer PRACH Physical Random Access Channel RACH Random AccessChannel RAN Random Access Network RRC Radio Resource Control RRM RadioResource Monitoring RSRP Radio Resource Mapping RSRQ Reference SignalReceived Quality SCell Secondary Cell SCG Secondary Cell Group SI SystemInformation SIB System Information Block SS Synchronization Signal TDDTime-Division Duplex UE User Equipment UL Uplink UL-SCH Uplink SharedChannel URLLC Ultra-Reliable and Low Latency Communication

General Architecture

The 3rd Generation Partnership Project (3GPP) develops technicalstandards for cellular telecommunications network technologies,including radio access, the core transport network, and servicecapabilities—including work on codecs, security, and quality of service.Recent radio access technology (RAT) standards include WCDMA (commonlyreferred as 3G), LTE (commonly referred as 4G), and LTE-Advancedstandards. 3GPP has begun working on the standardization of nextgeneration cellular technology, called NR, which is also referred to as“5G”. 3GPP NR standards development is expected to include thedefinition of next generation radio access technology (new RAT), whichis expected to include the provision of new flexible radio access below6 GHz, and the provision of new ultra-mobile broadband radio accessabove 6 GHz. The flexible radio access is expected to consist of a new,non-backwards compatible radio access in new spectrum below 6 GHz, andit is expected to include different operating modes that can bemultiplexed together in the same spectrum to address a broad set of 3GPPNR use cases with diverging requirements. The ultra-mobile broadband isexpected to include cmWave and mmWave spectrum that will provide theopportunity for ultra-mobile broadband access for, e.g., indoorapplications and hotspots. In particular, the ultra-mobile broadband isexpected to share a common design framework with the flexible radioaccess below 6 GHz, with cmWave and mmWave specific designoptimizations.

3GPP has identified a variety of use cases that NR is expected tosupport, resulting in a wide variety of user experience requirements fordata rate, latency, and mobility. The use cases include the followinggeneral categories: enhanced mobile broadband (e.g., broadband access indense areas, indoor ultra-high broadband access, broadband access in acrowd, 50+ Mbps everywhere, ultra-low cost broadband access, mobilebroadband in vehicles), critical communications, massive machine typecommunications, network operation (e.g., network slicing, routing,migration and interworking, energy savings), and enhancedvehicle-to-everything (eV2X) communications. Specific service andapplications in these categories include, e.g., monitoring and sensornetworks, device remote controlling, bi-directional remote controlling,personal cloud computing, video streaming, wireless cloud-based office,first responder connectivity, automotive ecall, disaster alerts,real-time gaming, multi-person video calls, autonomous driving,augmented reality, tactile internet, and virtual reality to name a few.All of these use cases and others are contemplated herein.

FIG. 1A illustrates one embodiment of an example communications system100 in which the methods and apparatuses described and claimed hereinmay be embodied. As shown, the example communications system 100 mayinclude wireless transmit/receive units (WTRUs) 102 a, 102 b, 102 c,and/or 102 d (which generally or collectively may be referred to as WTRU102), a radio access network (RAN) 103/104/105/103 b/104 b/105 b, a corenetwork 106/107/109, a public switched telephone network (PSTN) 108, theInternet 110, and other networks 112, though it will be appreciated thatthe disclosed embodiments contemplate any number of WTRUs, basestations, networks, and/or network elements. Each of the WTRUs 102 a,102 b, 102 c, 102 d, 102 e may be any type of apparatus or deviceconfigured to operate and/or communicate in a wireless environment.Although each WTRU 102 a, 102 b, 102 c, 102 d, 102 e is depicted inFIGS. 1A-E as a hand-held wireless communications apparatus, it isunderstood that with the wide variety of use cases contemplated for 5Gwireless communications, each WTRU may comprise or be embodied in anytype of apparatus or device configured to transmit and/or receivewireless signals, including, by way of example only, user equipment(UE), a mobile station, a fixed or mobile subscriber unit, a pager, acellular telephone, a personal digital assistant (PDA), a smartphone, alaptop, a tablet, a netbook, a notebook computer, a personal computer, awireless sensor, consumer electronics, a wearable device such as a smartwatch or smart clothing, a medical or eHealth device, a robot,industrial equipment, a drone, a vehicle such as a car, truck, train, orairplane, and the like.

The communications system 100 may also include a base station 114 a anda base station 114 b. Base stations 114 a may be any type of deviceconfigured to wirelessly interface with at least one of the WTRUs 102 a,102 b, 102 c to facilitate access to one or more communication networks,such as the core network 106/107/109, the Internet 110, and/or the othernetworks 112. Base stations 114 b may be any type of device configuredto wiredly and/or wirelessly interface with at least one of the RRHs(Remote Radio Heads) 118 a, 118 b and/or TRPs (Transmission andReception Points) 119 a, 119 b to facilitate access to one or morecommunication networks, such as the core network 106/107/109, theInternet 110, and/or the other networks 112. RRHs 118 a, 118 b may beany type of device configured to wirelessly interface with at least oneof the WTRU 102 c, to facilitate access to one or more communicationnetworks, such as the core network 106/107/109, the Internet 110, and/orthe other networks 112. TRPs 119 a, 119 b may be any type of deviceconfigured to wirelessly interface with at least one of the WTRU 102 d,to facilitate access to one or more communication networks, such as thecore network 106/107/109, the Internet 110, and/or the other networks112. By way of example, the base stations 114 a, 114 b may be a basetransceiver station (BTS), a Node-B, an eNode B, a Home Node B, a HomeeNode B, a site controller, an access point (AP), a wireless router, andthe like. While the base stations 114 a, 114 b are each depicted as asingle element, it will be appreciated that the base stations 114 a, 114b may include any number of interconnected base stations and/or networkelements.

The base station 114 a may be part of the RAN 103/104/105, which mayalso include other base stations and/or network elements (not shown),such as a base station controller (BSC), a radio network controller(RNC), relay nodes, etc. The base station 114 b may be part of the RAN103 b/104 b/105 b, which may also include other base stations and/ornetwork elements (not shown), such as a base station controller (BSC), aradio network controller (RNC), relay nodes, etc. The base station 114 amay be configured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The base station 114 b may be configured to transmit and/orreceive wired and/or wireless signals within a particular geographicregion, which may be referred to as a cell (not shown). The cell mayfurther be divided into cell sectors. For example, the cell associatedwith the base station 114 a may be divided into three sectors. Thus, inan embodiment, the base station 114 a may include three transceivers,e.g., one for each sector of the cell. In an embodiment, the basestation 114 a may employ multiple-input multiple output (MIMO)technology and, therefore, may utilize multiple transceivers for eachsector of the cell.

The base stations 114 a may communicate with one or more of the WTRUs102 a, 102 b, 102 c over an air interface 115/116/117, which may be anysuitable wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, cmWave,mmWave, etc.). The air interface 115/116/117 may be established usingany suitable radio access technology (RAT).

The base stations 114 b may communicate with one or more of the RRHs 118a, 118 b and/or TRPs 119 a, 119 b over a wired or air interface 115b/116 b/117 b, which may be any suitable wired (e.g., cable, opticalfiber, etc.) or wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, cmWave,mmWave, etc.). The air interface 115 b/116 b/117 b may be establishedusing any suitable radio access technology (RAT).

The RRHs 118 a, 118 b and/or TRPs 119 a, 119 b may communicate with oneor more of the WTRUs 102 c, 102 d over an air interface 115 c/116 c/117c, which may be any suitable wireless communication link (e.g., radiofrequency (RF), microwave, infrared (IR), ultraviolet (UV), visiblelight, cmWave, mmWave, etc.). The air interface 115 c/116 c/117 c may beestablished using any suitable radio access technology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 103/104/105 and the WTRUs 102a, 102 b, 102 c, or RRHs 118 a, 118 b and TRPs 119 a, 119 b in the RAN103 b/104 b/105 b and the WTRUs 102 c, 102 d, may implement a radiotechnology such as Universal Mobile Telecommunications System (UMTS)Terrestrial Radio Access (UTRA), which may establish the air interface115/116/117 or 115 c/116 c/117 c respectively using wideband CDMA(WCDMA). WCDMA may include communication protocols such as High-SpeedPacket Access (HSPA) and/or Evolved HSPA (HSPA+). HSPA may includeHigh-Speed Downlink Packet Access (HSDPA) and/or High-Speed UplinkPacket Access (HSUPA).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c, or RRHs 118 a, 118 b and TRPs 119 a, 119 b in the RAN 103 b/104 b/105b and the WTRUs 102 c, 102 d, may implement a radio technology such asEvolved UMTS Terrestrial Radio Access (E-UTRA), which may establish theair interface 115/116/117 or 115 c/116 c/117 c respectively using LongTerm Evolution (LTE) and/or LTE-Advanced (LTE-A). In the future, the airinterface 115/116/117 may implement 3GPP NR technology.

In an embodiment, the base station 114 a in the RAN 103/104/105 and theWTRUs 102 a, 102 b, 102 c, or RRHs 118 a, 118 b and TRPs 119 a, 119 b inthe RAN 103 b/104 b/105 b and the WTRUs 102 c, 102 d, may implementradio technologies such as IEEE 802.16 (e.g., Worldwide Interoperabilityfor Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO,Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), InterimStandard 856 (IS-856), Global System for Mobile communications (GSM),Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and thelike.

The base station 114 c in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, and the like. In anembodiment, the base station 114 c and the WTRUs 102 e, may implement aradio technology such as IEEE 802.11 to establish a wireless local areanetwork (WLAN). In an embodiment, the base station 114 c and the WTRUs102 d, may implement a radio technology such as IEEE 802.15 to establisha wireless personal area network (WPAN). In yet an embodiment, the basestation 114 c and the WTRUs 102 e, may utilize a cellular-based RAT(e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, etc.) to establish a picocellor femtocell. As shown in FIG. 1A, the base station 114 bmay have adirect connection to the Internet 110. Thus, the base station 114 c maynot be required to access the Internet 110 via the core network106/107/109.

The RAN 103/104/105 and/or RAN 103 b/104 b/105 b may be in communicationwith the core network 106/107/109, which may be any type of networkconfigured to provide voice, data, applications, and/or voice overinternet protocol (VoIP) services to one or more of the WTRUs 102 a, 102b, 102 c, 102 d. For example, the core network 106/107/109 may providecall control, billing services, mobile location-based services, pre-paidcalling, Internet connectivity, video distribution, etc., and/or performhigh-level security functions, such as user authentication.

Although not shown in FIG. 1A, it will be appreciated that the RAN103/104/105 and/or RAN 103 b/104 b/105 b and/or the core network106/107/109 may be in direct or indirect communication with other RANsthat employ the same RAT as the RAN 103/104/105 and/or RAN 103 b/104b/105 b or a different RAT. For example, in addition to being connectedto the RAN 103/104/105 and/or RAN 103 b/104 b/105 b, which may beutilizing an E-UTRA radio technology, the core network 106/107/109 mayalso be in communication with another RAN (not shown) employing a GSMradio technology.

The core network 106/107/109 may also serve as a gateway for the WTRUs102 a, 102 b, 102 c, 102 d, 102 e to access the PSTN 108, the Internet110, and/or other networks 112. The PSTN 108 may includecircuit-switched telephone networks that provide plain old telephoneservice (POTS). The Internet 110 may include a global system ofinterconnected computer networks and devices that use commoncommunication protocols, such as the transmission control protocol(TCP), user datagram protocol (UDP) and the internet protocol (IP) inthe TCP/IP internet protocol suite. The networks 112 may include wiredor wireless communications networks owned and/or operated by otherservice providers. For example, the networks 112 may include anothercore network connected to one or more RANs, which may employ the sameRAT as the RAN 103/104/105 and/or RAN 103 b/104 b/105 b or a differentRAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, e.g., theWTRUs 102 a, 102 b, 102 c, 102 d, and 102 e may include multipletransceivers for communicating with different wireless networks overdifferent wireless links. For example, the WTRU 102 e shown in FIG. 1Amay be configured to communicate with the base station 114 a, which mayemploy a cellular-based radio technology, and with the base station 114c, which may employ an IEEE 802 radio technology.

FIG. 1B is a block diagram of an example apparatus or device configuredfor wireless communications in accordance with the embodimentsillustrated herein, such as for example, a WTRU 102. As shown in FIG.1B, the example WTRU 102 may include a processor 118, a transceiver 120,a transmit/receive element 122, a speaker/microphone 124, a keypad 126,a display/touchpad/indicators 128, non-removable memory 130, removablememory 132, a power source 134, a global positioning system (GPS)chipset 136, and other peripherals 138. It will be appreciated that theWTRU 102 may include any sub-combination of the foregoing elements whileremaining consistent with an embodiment. Also, embodiments contemplatethat the base stations 114 a and 114 b, and/or the nodes that basestations 114 a and 114 b may represent, such as but not limited totransceiver station (BTS), a Node-B, a site controller, an access point(AP), a home node-B, an evolved home node-B (eNodeB), a home evolvednode-B (HeNB), a home evolved node-B gateway, and proxy nodes, amongothers, may include some or all of the elements depicted in FIG. 1B anddescribed herein.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 115/116/117. For example, in an embodiment,the transmit/receive element 122 may be an antenna configured totransmit and/or receive RF signals. In an embodiment, thetransmit/receive Although not shown in FIG. 1A, it will be appreciatedthat the RAN 103/104/105 and/or the core network 106/107/109 may be indirect or indirect communication with other RANs that employ the sameRAT as the RAN 103/104/105 or a different RAT. For example, in additionto being connected to the RAN 103/104/105, which may be utilizing anE-UTRA radio technology, the core network 106/107/109 may also be incommunication with another RAN (not shown) employing a GSM radiotechnology.

The core network 106/107/109 may also serve as a gateway for the WTRUs102 a, 102 b, 102 c, 102 d to access the PSTN 108, the Internet 110,and/or other networks 112. The PSTN 108 may include circuit-switchedtelephone networks that provide plain old telephone service (POTS). TheInternet 110 may include a global system of interconnected computernetworks and devices that use common communication protocols, such asthe transmission control protocol (TCP), user datagram protocol (UDP)and the internet protocol (IP) in the TCP/IP internet protocol suite.The networks 112 may include wired or wireless communications networksowned and/or operated by other service providers. For example, thenetworks 112 may include another core network connected to one or moreRANs, which may employ the same RAT as the RAN 103/104/105 or adifferent RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, e.g., theWTRUs 102 a, 102 b, 102 c, and 102 d may include multiple transceiversfor communicating with different wireless networks over differentwireless links. For example, the WTRU 102 c shown in FIG. 1A may beconfigured to communicate with the base station 114 a, which may employa cellular-based radio technology, and with the base station 114 b,which may employ an IEEE 802 radio technology.

FIG. 1B is a block diagram of an example apparatus or device configuredfor wireless communications in accordance with the embodimentsillustrated herein, such as for example, a WTRU 102. As shown in FIG.1B, the example WTRU 102 may include a processor 118, a transceiver 120,a transmit/receive element 122, a speaker/microphone 124, a keypad 126,a display/touchpad/indicators 128, non-removable memory 130, removablememory 132, a power source 134, a global positioning system (GPS)chipset 136, and other peripherals 138. It will be appreciated that theWTRU 102 may include any sub-combination of the foregoing elements whileremaining consistent with an embodiment. Also, embodiments contemplatethat the base stations 114 a and 114 b, and/or the nodes that basestations 114 a and 114 b may represent, such as but not limited totransceiver station (BTS), a Node-B, a site controller, an access point(AP), a home node-B, an evolved home node-B (eNodeB), a home evolvednode-B (HeNB), a home evolved node-B gateway, and proxy nodes, amongothers, may include some or all of the elements depicted in FIG. 1B anddescribed herein.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 115/116/117. For example, in an embodiment,the transmit/receive element 122 may be an antenna configured totransmit and/or receive RF signals. In an embodiment, thetransmit/receive element 122 may be an emitter/detector configured totransmit and/or receive IR, UV, or visible light signals, for example.In yet an embodiment, the transmit/receive element 122 may be configuredto transmit and receive both RF and light signals. It will beappreciated that the transmit/receive element 122 may be configured totransmit and/or receive any combination of wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in an embodiment, the WTRU 102 may includetwo or more transmit/receive elements 122 (e.g., multiple antennas) fortransmitting and receiving wireless signals over the air interface115/116/117.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad/indicators 128 (e.g., a liquid crystal display(LCD) display unit or organic light-emitting diode (OLED) display unit).The processor 118 may also output user data to the speaker/microphone124, the keypad 126, and/or the display/touchpad/indicators 128. Inaddition, the processor 118 may access information from, and store datain, any type of suitable memory, such as the non-removable memory 130and/or the removable memory 132. The non-removable memory 130 mayinclude random-access memory (RAM), read-only memory (ROM), a hard disk,or any other type of memory storage device. The removable memory 132 mayinclude a subscriber identity module (SIM) card, a memory stick, asecure digital (SD) memory card, and the like. In an embodiment, theprocessor 118 may access information from, and store data in, memorythat is not physically located on the WTRU 102, such as on a server or ahome computer (not shown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries, solar cells, fuel cells, and thelike.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 115/116/117from a base station (e.g., base stations 114 a, 114 b) and/or determineits location based on the timing of the signals being received from twoor more nearby base stations. It will be appreciated that the WTRU 102may acquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include varioussensors such as an accelerometer, biometrics (e.g., finger print)sensors, an e-compass, a satellite transceiver, a digital camera (forphotographs or video), a universal serial bus (USB) port or otherinterconnect interfaces, a vibration device, a television transceiver, ahands free headset, a Bluetooth® module, a frequency modulated (FM)radio unit, a digital music player, a media player, a video game playermodule, an Internet browser, and the like.

The WTRU 102 may be embodied in other apparatuses or devices, such as asensor, consumer electronics, a wearable device such as a smart watch orsmart clothing, a medical or eHealth device, a robot, industrialequipment, a drone, a vehicle such as a car, truck, train, or airplane.The WTRU 102 may connect to other components, modules, or systems ofsuch apparatuses or devices via one or more interconnect interfaces,such as an interconnect interface that may comprise one of theperipherals 138.

FIG. 1C is a system diagram of the RAN 103 and the core network 106according to an embodiment. As noted above, the RAN 103 may employ aUTRA radio technology to communicate with the WTRUs 102 a, 102 b, and102 c over the air interface 115. The RAN 103 may also be incommunication with the core network 106. As shown in FIG. 1C, the RAN103 may include Node-Bs 140 a, 140 b, 140 c, which may each include oneor more transceivers for communicating with the WTRUs 102 a, 102 b, 102c over the air interface 115. The Node-Bs 140 a, 140 b, 140 c may eachbe associated with a particular cell (not shown) within the RAN 103. TheRAN 103 may also include RNCs 142 a, 142 b. It will be appreciated thatthe RAN 103 may include any number of Node-Bs and RNCs while remainingconsistent with an embodiment.

As shown in FIG. 1C, the Node-Bs 140 a, 140 b may be in communicationwith the RNC 142 a. Additionally, the Node-B 140 c may be incommunication with the RNC 142 b. The Node-Bs 140 a, 140 b, 140 c maycommunicate with the respective RNCs 142 a, 142 b via an Iub interface.The RNCs 142 a, 142 bmay be in communication with one another via an Iurinterface. Each of the RNCs 142 a, 142 b may be configured to controlthe respective Node-Bs 140 a, 140 b, 140 c to which it is connected. Inaddition, each of the RNCs 142 a, 142 b may be configured to carry outor support other functionality, such as outer loop power control, loadcontrol, admission control, packet scheduling, handover control,macro-diversity, security functions, data encryption, and the like.

The core network 106 shown in FIG. 1C may include a media gateway (MGW)144, a mobile switching center (MSC) 146, a serving GPRS support node(SGSN) 148, and/or a gateway GPRS support node (GGSN) 150. While each ofthe foregoing elements are depicted as part of the core network 106, itwill be appreciated that any one of these elements may be owned and/oroperated by an entity other than the core network operator.

The RNC 142 a in the RAN 103 may be connected to the MSC 146 in the corenetwork 106 via an IuCS interface. The MSC 146 may be connected to theMGW 144. The MSC 146 and the MGW 144 may provide the WTRUs 102 a, 102 b,102 c with access to circuit-switched networks, such as the PSTN 108, tofacilitate communications between the WTRUs 102 a, 102 b, 102 c andtraditional land-line communications devices.

The RNC 142 a in the RAN 103 may also be connected to the SGSN 148 inthe core network 106 via an IuPS interface. The SGSN 148 may beconnected to the GGSN 150. The SGSN 148 and the GGSN 150 may provide theWTRUs 102 a, 102 b, 102 c with access to packet-switched networks, suchas the Internet 110, to facilitate communications between and the WTRUs102 a, 102 b, 102 c and IP-enabled devices.

As noted above, the core network 106 may also be connected to thenetworks 112, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

FIG. 1D is a system diagram of the RAN 104 and the core network 107according to an embodiment. As noted above, the RAN 104 may employ anE-UTRA radio technology to communicate with the WTRUs 102 a, 102 b, and102 c over the air interface 116. The RAN 104 may also be incommunication with the core network 107.

The RAN 104 may include eNode-Bs 160 a, 160 b, 160 c, though it will beappreciated that the RAN 104 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 160 a, 160 b, 160c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 cover the air interface 116. In an embodiment,the eNode-Bs 160 a, 160 b, 160 c may implement MIMO technology. Thus,the eNode-B 160 a, for example, may use multiple antennas to transmitwireless signals to, and receive wireless signals from, the WTRU 102 a.

Each of the eNode-Bs 160 a, 160 b, and 160 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the uplink and/or downlink, and the like. As shown in FIG. 1D, theeNode-Bs 160 a, 160 b, 160 c may communicate with one another over an X2interface.

The core network 107 shown in FIG. 1D may include a mobility managementgateway (MME) 162, a serving gateway 164, and a packet data network(PDN) gateway 166. While each of the foregoing elements are depicted aspart of the core network 107, it will be appreciated that any one ofthese elements may be owned and/or operated by an entity other than thecore network operator.

The MME 162 may be connected to each of the eNode-Bs 160 a, 160 b, and160 c in the RAN 104 via an S1 interface and may serve as a controlnode. For example, the MME 162 may be responsible for authenticatingusers of the WTRUs 102 a, 102 b, 102 c, bearer activation/deactivation,selecting a particular serving gateway during an initial attach of theWTRUs 102 a, 102 b, 102 c, and the like. The MME 162 may also provide acontrol plane function for switching between the RAN 104 and other RANs(not shown) that employ other radio technologies, such as GSM or WCDMA.

The serving gateway 164 may be connected to each of the eNode-Bs 160 a,160 b, and 160 c in the RAN 104 via the S1 interface. The servinggateway 164 may generally route and forward user data packets to/fromthe WTRUs 102 a, 102 b, 102 c. The serving gateway 164 may also performother functions, such as anchoring user planes during inter-eNode Bhandovers, triggering paging when downlink data is available for theWTRUs 102 a, 102 b, 102 c, managing and storing contexts of the WTRUs102 a, 102 b, 102 c, and the like.

The serving gateway 164 may also be connected to the PDN gateway 166,which may provide the WTRUs 102 a, 102 b, 102 c with access topacket-switched networks, such as the Internet 110, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and IP-enableddevices.

The core network 107 may facilitate communications with other networks.For example, the core network 107 may provide the WTRUs 102 a, 102 b,102 c with access to circuit-switched networks, such as the PSTN 108, tofacilitate communications between the WTRUs 102 a, 102 b, 102 c andtraditional land-line communications devices. For example, the corenetwork 107 may include, or may communicate with, an IP gateway (e.g.,an IP multimedia subsystem (IMS) server) that serves as an interfacebetween the core network 107 and the PSTN 108. In addition, the corenetwork 107 may provide the WTRUs 102 a, 102 b, 102 c with access to thenetworks 112, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

FIG. 1E is a system diagram of the RAN 105 and the core network 109according to an embodiment. The RAN 105 may be an access service network(ASN) that employs IEEE 802.16 radio technology to communicate with theWTRUs 102 a, 102 b, and 102 c over the air interface 117. As will befurther discussed below, the communication links between the differentfunctional entities of the WTRUs 102 a, 102 b, 102 c, the RAN 105, andthe core network 109 may be defined as reference points.

As shown in FIG. 1E, the RAN 105 may include base stations 180 a, 180 b,180 c, and an ASN gateway 182, though it will be appreciated that theRAN 105 may include any number of base stations and ASN gateways whileremaining consistent with an embodiment. The base stations 180 a, 180 b,180 c may each be associated with a particular cell in the RAN 105 andmay include one or more transceivers for communicating with the WTRUs102 a, 102 b, 102 c over the air interface 117. In an embodiment, thebase stations 180 a, 180 b, 180 c may implement MIMO technology. Thus,the base station 180 a, for example, may use multiple antennas totransmit wireless signals to, and receive wireless signals from, theWTRU 102 a. The base stations 180 a, 180 b, 180 c may also providemobility management functions, such as handoff triggering, tunnelestablishment, radio resource management, traffic classification,quality of service (QoS) policy enforcement, and the like. The ASNgateway 182 may serve as a traffic aggregation point and may beresponsible for paging, caching of subscriber profiles, routing to thecore network 109, and the like.

The air interface 117 between the WTRUs 102 a, 102 b, 102 c and the RAN105 may be defined as an R1 reference point that implements the IEEE802.16 specification. In addition, each of the WTRUs 102 a, 102 b, and102 c may establish a logical interface (not shown) with the corenetwork 109. The logical interface between the WTRUs 102 a, 102 b, 102 cand the core network 109 may be defined as an R2 reference point, whichmay be used for authentication, authorization, IP host configurationmanagement, and/or mobility management.

The communication link between each of the base stations 180 a, 180 b,and 180 c may be defined as an R8 reference point that includesprotocols for facilitating WTRU handovers and the transfer of databetween base stations. The communication link between the base stations180 a, 180 b, 180 c and the ASN gateway 182 may be defined as an R6reference point. The R6 reference point may include protocols forfacilitating mobility management based on mobility events associatedwith each of the WTRUs 102 a, 102 b, 102 c.

As shown in FIG. 1E, the RAN 105 may be connected to the core network109. The communication link between the RAN 105 and the core network 109may defined as an R3 reference point that includes protocols forfacilitating data transfer and mobility management capabilities, forexample. The core network 109 may include a mobile IP home agent(MIP-HA) 184, an authentication, authorization, accounting (AAA) server186, and a gateway 188. While each of the foregoing elements aredepicted as part of the core network 109, it will be appreciated thatany one of these elements may be owned and/or operated by an entityother than the core network operator.

The MIP-HA may be responsible for IP address management, and may enablethe WTRUs 102 a, 102 b, and 102 c to roam between different ASNs and/ordifferent core networks. The MIP-HA 184 may provide the WTRUs 102 a, 102b, 102 c with access to packet-switched networks, such as the Internet110, to facilitate communications between the WTRUs 102 a, 102 b, 102 cand IP-enabled devices. The AAA server 186 may be responsible for userauthentication and for supporting user services. The gateway 188 mayfacilitate interworking with other networks. For example, the gateway188 may provide the WTRUs 102 a, 102 b, 102 c with access tocircuit-switched networks, such as the PSTN 108, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and traditionalland-line communications devices. In addition, the gateway 188 mayprovide the WTRUs 102 a, 102 b, 102 c with access to the networks 112,which may include other wired or wireless networks that are owned and/oroperated by other service providers.

Although not shown in FIG. 1E, it will be appreciated that the RAN 105may be connected to other ASNs and the core network 109 may be connectedto other core networks. The communication link between the RAN 105 theother ASNs may be defined as an R4 reference point, which may includeprotocols for coordinating the mobility of the WTRUs 102 a, 102 b, 102 cbetween the RAN 105 and the other ASNs. The communication link betweenthe core network 109 and the other core networks may be defined as an R5reference, which may include protocols for facilitating interworkingbetween home core networks and visited core networks.

The core network entities described herein and illustrated in FIGS. 1A,1C, 1D, and 1E are identified by the names given to those entities incertain existing 3GPP specifications, but it is understood that in thefuture those entities and functionalities may be identified by othernames and certain entities or functions may be combined in futurespecifications published by 3GPP, including future 3GPP NRspecifications. Thus, the particular network entities andfunctionalities described and illustrated in FIGS. 1A, 1B, 1C, 1D, and1E are provided by way of example only, and it is understood that thesubject matter disclosed and claimed herein may be embodied orimplemented in any similar communication system, whether presentlydefined or defined in the future.

FIG. 10F is a block diagram of an exemplary computing system 90 in whichone or more apparatuses of the communications networks illustrated inFIGS. 1A, 1C, 1D and 1E may be embodied, such as certain nodes orfunctional entities in the RAN 103/104/105, Core Network 106/107/109,PSTN 108, Internet 110, or Other Networks 112. Computing system 90 maycomprise a computer or server and may be controlled primarily bycomputer readable instructions, which may be in the form of software,wherever, or by whatever means such software is stored or accessed. Suchcomputer readable instructions may be executed within a processor 91, tocause computing system 90 to do work. The processor 91 may be a generalpurpose processor, a special purpose processor, a conventionalprocessor, a digital signal processor (DSP), a plurality ofmicroprocessors, one or more microprocessors in association with a DSPcore, a controller, a microcontroller, Application Specific IntegratedCircuits (ASICs), Field Programmable Gate Array (FPGAs) circuits, anyother type of integrated circuit (IC), a state machine, and the like.The processor 91 may perform signal coding, data processing, powercontrol, input/output processing, and/or any other functionality thatenables the computing system 90 to operate in a communications network.Coprocessor 81 is an optional processor, distinct from main processor91, that may perform additional functions or assist processor 91.Processor 91 and/or coprocessor 81 may receive, generate, and processdata related to the methods and apparatuses disclosed herein.

In operation, processor 91 fetches, decodes, and executes instructions,and transfers information to and from other resources via the computingsystem's main data-transfer path, system bus 80. Such a system busconnects the components in computing system 90 and defines the mediumfor data exchange. System bus 80 typically includes data lines forsending data, address lines for sending addresses, and control lines forsending interrupts and for operating the system bus. An example of sucha system bus 80 is the PCI (Peripheral Component Interconnect) bus.

Memories coupled to system bus 80 include random access memory (RAM) 82and read only memory (ROM) 93. Such memories include circuitry thatallows information to be stored and retrieved. ROMs 93 generally containstored data that cannot easily be modified. Data stored in RAM 82 can beread or changed by processor 91 or other hardware devices. Access to RAM82 and/or ROM 93 may be controlled by memory controller 92. Memorycontroller 92 may provide an address translation function thattranslates virtual addresses into physical addresses as instructions areexecuted. Memory controller 92 may also provide a memory protectionfunction that isolates processes within the system and isolates systemprocesses from user processes. Thus, a program running in a first modecan access only memory mapped by its own process virtual address space;it cannot access memory within another process's virtual address spaceunless memory sharing between the processes has been set up.

In addition, computing system 90 may contain peripherals controller 83responsible for communicating instructions from processor 91 toperipherals, such as printer 94, keyboard 84, mouse 95, and disk drive85.

Display 86, which is controlled by display controller 96, is used todisplay visual output generated by computing system 90. Such visualoutput may include text, graphics, animated graphics, and video. Thevisual output may be provided in the form of a graphical user interface(GUI). One example of the GUI is shown in FIG. 25. Display 86 may beimplemented with a CRT-based video display, an LCD-based flat-paneldisplay, gas plasma-based flat-panel display, or a touch-panel. Displaycontroller 96 includes electronic components required to generate avideo signal that is sent to display 86.

Still further, computing system 90 may contain communication circuitry,such as for example a network adapter 97, that may be used to connectcomputing system 90 to an external communications network, such as theRAN 103/104/105, Core Network 106/107/109, PSTN 108, Internet 110, orOther Networks 112 of FIGS. 1A, 1B, 1C, 1D, and 1E, to enable thecomputing system 90 to communicate with other nodes or functionalentities of those networks. The communication circuitry, alone or incombination with the processor 91, may be used to perform thetransmitting and receiving steps of certain apparatuses, nodes, orfunctional entities described herein.

It is understood that any or all of the apparatuses, systems, methodsand processes described herein may be embodied in the form of computerexecutable instructions (e.g., program code) stored on acomputer-readable storage medium which instructions, when executed by aprocessor, such as processors 118 or 91, cause the processor to performand/or implement the systems, methods and processes described herein.Specifically, any of the steps, operations or functions described hereinmay be implemented in the form of such computer executable instructions,executing on the processor of an apparatus or computing systemconfigured for wireless and/or wired network communications. Computerreadable storage media include volatile and nonvolatile, removable andnon-removable media implemented in any non-transitory (e.g., tangible orphysical) method or technology for storage of information, but suchcomputer readable storage media do not includes signals. Computerreadable storage media include, but are not limited to, RAM, ROM,EEPROM, flash memory or other memory technology, CD-ROM, digitalversatile disks (DVD) or other optical disk storage, magnetic cassettes,magnetic tape, magnetic disk storage or other magnetic storage devices,or any other tangible or physical medium which can be used to store thedesired information and which can be accessed by a computing system.

Unlicensed Spectrum in LTE

As specified in 3GPP TS 36.213, Physical Layer Procedures, for Release13 and Release 14, Licensed-assisted access (LAA) targets the carrieraggregation (CA) operation in which one or more low power secondarycells (SCells) operate in unlicensed spectrum in sub 6 GHz. LAAdeployment scenarios encompass scenarios with and without macrocoverage, both outdoor and indoor small cell deployments, and bothco-location and non-co-location (with ideal backhaul) between licensedand unlicensed carriers, as shown in FIGS. 2A-D.

Scenario 1 of FIG. 2A depicts carrier aggregation between licensed macrocell (F1) and unlicensed small cell (F3). Meanwhile, scenario 2 of FIG.2B depicts carrier aggregation between licensed small cell (F2) andunlicensed small cell (F3) without macro cell coverage. Subsequently,scenario 3 of FIG. 2C depicts a licensed macro cell and small cell (F1),with carrier aggregation between licensed small cell (F1) and unlicensedsmall cell (F3)

Further, scenario 4 FIG. 2D depicts a licensed macro cell (F1), licensedsmall cell (F2), and unlicensed small cell (F3). Scenario 4 includescarrier aggregation between licensed small cell (F2) and unlicensedsmall cell (F3). If there is ideal backhaul between macro cell and smallcell, there can be carrier aggregation between macro cell (F1), licensedsmall cell (F2) and unlicensed small cell (F3). If dual connectivity isenabled, there can be dual connectivity between macro cell and smallcell.

Since the unlicensed band can be utilized by different deploymentsspecified by different standards, several regulatory requirements areimposed to insure fair coexistence between all incumbent users. Forexample, these regulatory requirements include constraints on transmitpower mask, transmit bandwidth, interference with weather radars, etc.

In addition, another main requirement is a channel access procedure. Forexample, the LBT procedure is defined as a mechanism by which anequipment applies a clear channel assessment (CCA) check before usingthe channel. The CCA utilizes energy detection to determine the presenceor absence of other signals on a channel. In turn, this determineswhether a channel is occupied or clear, respectively. European andJapanese regulations mandate the usage of LBT in the unlicensed bands.Apart from regulatory requirements, carrier sensing via LBT is one wayfor fair sharing of the unlicensed spectrum. Hence, it is consideredimportant for fair and friendly operation in the unlicensed spectrum ina single global solution framework.

In Release 14, several channel access procedures are introduced to beperformed by eNB and UE for both downlink (DL) and UL transmissions,respectively. The main channel access procedure is described in Section15 of TS 36.213 Release 14.

Unlicensed Spectrum in NR

In mmWave, there is a wide range of unlicensed spectrum that can befurther utilized to attain higher data rates than attained by operatingin sub 6 GHz frequency band. Consequently, RAN #76 introduced a new SIfor NR based access to unlicensed spectrum. The main goals of thecurrent SI include studying the different physical channels andprocedures in NR-U, and how they have to be modified. The goals alsoinclude introducing new physical channels or procedures to cope withNR-U challenges. This accounts for operating in mmWave deploying narrowbeams for transmission and reception above 6 GHZ up to 52.6 GHz or evenabove 52.6 GHz bands. Procedures to enhance the co-existence betweenNR-U and other technologies operating in the unlicensed, e.g., Wi-Fidevices, LTE-based LAA devices, other NR-U devices, etc., and meet theregulatory requirements are currently under study.

Synchronization Information and Discovery Reference Signal with HighPriority

According to an aspect of the application in NR, SSB allows the UE toobtain pertinent information of synchronization, frame boundary etc. InNR-U, UEs in different services (e.g., NR, WIFI) share the sameunlicensed spectrum. Accordingly, the UE and gNB perform LBT to makesure the channel is not occupied before transmission. This featureintroduces uncertainty to the periodic or semi-persistent scheduledtransmissions such as SSB transmission. Considering the essentials ofSSB in cell search, synchronization etc., it is envisaged that the SSBtransmission may be categorized with high priority in channel accesspriority class with no backoff time or have a smallest backoff timeamong all the channel accessing backoff times.

In an embodiment, the SSB will have a higher possibility to betransmitted with the tradeoff that having a smaller maximum channeloccupation time (MCOT) T_(mcot), e.g., T_(mcot)=2 ms for channel accesspriority class 1 in LAA. In NR, the SSBs are transmitted in the SSBburst set which may last up to 5 ms. The whole SSB burst settransmission may not be able to fit into the T_(mcot) with priorityclass 1, e.g., subcarrier spacing case A and case D. Therefore, it isenvisaged in NR-U that the SSB burst set may be divided and transmittedin several subsets to fulfill the T_(mcot) requirement. An example isshown in FIGS. 3A-B using subcarrier spacing case A in NR. Thesubcarrier spacing is 15 Khz and carrier frequency 3 GHz≤f≤6 GHz. Inthis case, the whole SSB burst set contains 8 SSBs which can't fill intothe T_(mcot). The gNB may divide the SSB burst set into two SSB burstsubsets and each SSB burst subset's duration is less than 2 ms. The gNBperforms LBT and transmits a first subset and repeats the procedure forthe second subset.

Alternatively, the gNB may divide the SSB burst set into finergranularity such as 4 subsets where each subset contains 2 SSBs. It isenvisaged that each subset may contain one or multiple SSB bursts. Theperiodicity of the SSB burst subset may be the same as the periodicityof the SSB burst set. Once the SSB burst subsets are determined, it maybe transmitted in one of the following exemplary ways:

In a first way, a UE may be configured by the gNB to receive multipleSSB burst subsets in one radio frame. An example of this way isexemplarily shown in FIG. 3A. In this case, a UE may be configured withone occasion to monitor all the SSB burst subsets

In a second way, a UE may be configured by the gNB to receive the SSBburst subsets in different radio frames. An example of this way isexemplarily shown in FIG. 3B. In this case, a UE may be configured withdifferent occasions to monitor different the SSB burst subsets

For the case where the whole SSB burst set can be filled into theT_(mcot) such as the subcarrier spacing case B, C and E, the SSB burstset may also be divided into multiple SSB burst subsets and transmitted,e.g., the gNB may transmit the SSB burst subset after the LBT with achannel occupation duration shorter than the T_(mcot).

STTC

According to yet another embodiment, to further enhance reliability ofthe SSB transmission, it is envisaged the SSB burst set/subset may betransmitted in the STTC (SSB Transmission Timing Configuration). Anexample depiction is provided in FIG. 4. The time duration of the STTCmay be pre-configured or specified. Alternatively, it may beconfigured/signaled by the gNB through RRC signaling, and/or MAC CE. Forexample, a UE may be configured with RRC messageSSB_Tansmission_Timing_duration to indicate the duration of the STTCwhich may be 5 ms, 8 ms or etc. Within one STTC, multiple LBTs may beperformed. The SSB burst set/subset may be transmitted after successfulLBT and one or more SSB burst set/subset may be transmitted within oneSTTC. In an alternative embodiment, instead of only monitoring the SSBin one fixed location in time, a UE may monitor the SSB multiple timeswithin the configured STTC to detect the transmitted SSB.

SSB Burst Set/Subset Transmission Slided Within the STTC

According to even another aspect of the application in NR, multiple SSBsare bundled in the SS burst set. The SS burst set is transmitted at thepre-defined/configured location. In NR-U, the gNB performs LBT beforethe SSB Burst transmission. The SSB transmission may still be bundledtogether. An example of success LBT for bundled SSB transmission at thepre-defined/configured location is shown in FIG. 5.

According to this example in FIG. 5, omni-direction LBT or beam-baseddirectional LBT may be performed before the configured SSB transmission.With the successful LBT on the omni-direction or all the directionalbeams, the SSB can be transmitted on the pre-defined/configured locationas an SSB burst set. No additional LBT is need during this SSB burst settransmission if the gNB is able to occupy the channel in this duration.It is envisaged that bundled SSB transmissions may be shifted in theSTTC. In this case, the SSB index order is not changed within thebundled SSB transmission (e.g., SSB #0, SSB #1, SSB #2, SSB #3), but SSB#0 location can be changed within the radio frame. Multiple LBT may beperformed by the gNB within the STTC. The LBT may be performed by one ofthe following exemplary options:

Option 1: The gNB may perform LBT right before the possible SSBtransmission location with one attempt. The possible SSB transmissionlocation may be determined based on the resolution of the offset. Thismay be pre-defined in the spec or may be configured in the STTC. Thepossible location for SSBi=SSBi location specified +j*slot, where j isthe iterations of LBT process after the initial LBT failure for SSBi.This assumes the SSB 0 is configured to be transmitted at symbol 4 ofslot 1. If the offset is a number of slots, the first possible SSBtransmission location for SSB 0 is at symbol 4 of slot 1, and the secondpossible SSB transmission location for SSB 0 is at symbol 4 of slot 2etc. If the LBT succeeds, the gNB will transmit the shifted SSB. If theLBT fails, the gNB may perform LBT before the next possible SSBtransmission location. This option is exemplarily depicted in FIG. 6.The gNB may perform 25 μs LBT with no backoff time at symbol 3 in slot0. The LBT can be either omni-direction LBT or beam-based directionalLBT. If it fails, the gNB may perform 25 μs LBT with no backoff time atsymbol 3 in slot 1. If the LBT succeeds in slot 1, the bundled SSB maybe transmitted starting from the symbol 4 of slot 1 to the symbol 9 ofslot 2.

Option 2: The gNB may perform LBT before the possible SSB transmissionlocation with multiple attempts. The possible SSB transmission locationmay be determined based on the resolution of the offset which may bepre-defined in the spec or may be configured in the STTC. The possiblelocation for SSBi=SSBi location specified +j*slot, where j is theiterations of LBT process after the initial LBT failure for SSBi. If theLBT succeeds earlier than the possible SSB transmission location,reservation signal will be transmitted to occupy the channel and SSBwill be transmitted on the possible SSB transmission location. Anexemplary illustration is shown in FIG. 7. The gNB may perform 25 μs LBTwith no backoff time at symbol 3 in slot 0. The LBT can be eitheromni-direction LBT or beam-based directional LBT. If it fails, the gNBmay continue to perform LBT. If the LBT succeeds at symbol 0 in slot 1,reservation signal may be transmitted to hold the channel which may lasta few number of symbols. Note the reservation signal cannot bearbitrarily long due to the limitation of the MCOT. Ultimately, thebundled SSB may be transmitted starting from the symbol 4 of slot 1 tothe symbol 9 of slot 2.

In an embodiment, the bundled SSB transmission is shifted in the STTC.In this scenario, a fixed offset Δ is introduced to all the SSBs fromthe radio frame boundary. For example, the offset may be in number ofslots as shown in FIG. 6 and FIG. 7. In this case, Δ32 k slot(s) wherek=0, 1, 2, . . . , K−1.

In an alternative embodiment, the offset may be in number of SSBlocations. The possible SSB transmission location may be determinedbased on the resolution of the offset and may be predefined in the specor may be configured in the STTC. This assumes SSB 0 is configured to betransmitted at symbol 4 of slot 1. If the offset is the number of SSBlocations, the first possible SSB transmission location determined bythe offset resolution and iterations of LBT process after the initialLBT failure for SSB 0 is at symbol 8 of slot 0. The second possible SSBtransmission location for SSB 0 is at symbol 4 of slot 1, etc. Anexemplary embodiment is shown in FIG. 8. The LBT may fail at symbol 3 inslot 0 but succeed at symbol 7 in slot 0. In this scenario, the bundledSSB may be shifted by one SSB location and transmitted. In other words,the SSB 0 is transmitted on the location supposed to transmit for SSB1,the SSB 1 is transmitted on the location supposed to transmit SSB 2,etc. The offset will be the SSB index difference between the scheduleSSB index and the actual transmitted SSB index.

In the example shown in FIG. 8, the offset is equal to 1. The offset isa logic value, a UE need to map the logic value to physical locationbased on a specific SSB configuration. In this example, LBT is performedright before the possible SSB transmission location determined by theoffset resolution and iterations of LBT process after the initial LBTfailure and no reservation signal is used. In an alternative embodiment,a reservation signal may be employed for this solution.

In another case, the SSB index order may be changed within the bundledSSB transmission when the SSB bundle is shifted. For example, the SSBindex order may be cyclically shifted, e.g., the cyclically shifted SSBindex order may be SSB #1, SSB #2, SSB #3, SSB #0.

According to an embodiment, to determine the frame boundary, a UE needsto be aware of the information of both the SSB block index and offset Δ.An example of offsetΔ is shown in FIG. 8. To achieve the information ofthe offset, a UE may indicate the value of offset Δ using one of thefollowing options:

Option 1: The value of offset Δ may be indicated by the payload of PBCH.For example, PBCH of all beams may carry same payload and indicate theoffset from the frame boundary (2 bits for 4 locations). For example, ifthere are 4 or 8 SSBs within the SSB burst set transmission, thereserved PBCH payload bits (ā_(Ā+6) , ā_(Ā+7) may be used to indicatethe offset Δ. A UE may determine the frame boundary with the informationof SSB block index and offset Δ. Alternatively, some additional fieldmay be added to the PBCH to convey the value of offset Δ.

Option 1a: The offset Δ may be indicated by applying a mask to the CRCbits of the PBCH payload. The UE decodes the PBCH and applies differentmasks to the CRC. The mask that makes the CRC checksum successful isused to indicate the offset Δ.

Option 2: The value of offset Δ may be indicated through PBCH DMRS. ThePBCH DMRS may be initialized by the offset Δ. An example is providedbelow as follows:

c _(init)=2¹¹(i _(SSB)+8Δ+1)(└N _(ID) ^(cell)/4┘+1)+2⁶(i _(SSb)+8Δ+1)+(N_(ID) ^(cell) mod 4)

When a UE detects the PBCH DMRS by blindly cross-correlation, itdetermines the offset value based on the PBCH DMRS sequence.

Option 3: The value of offset Δ may be jointly indicated through PBCHDMRS and payload of PBCH, e.g., assume 3 bits are needed to indicate theoffset Δ, the two MSB may be indicated in the payload of the PBCH. Theone LSB may be indicated by the PBCH DMRS by using different sequencesinitialized by LSB of the offset.

Option 4: This is based upon the requirement of channel occupation inthe frequency of the unlicensed band. In NR-U, the SSB may be repeatedin the frequency domain and transmitted on the same beam to achieve therequirement. An exemplary embodiment is depicted in FIG. 9.

In NR, the PBCH DMRS is used to blindly detect up to 3 LSB bits of theSSB index. If the offset Δ also must be indicated, the number of blinddecoding increases and the PBCH DMRS may not be sufficiently robust. Itis envisaged that the SSB repetition may advantageously be employed toindicate the offset Δ.

If the SSB is repeated, spreading codes may be applied to the PBCH DMRS.Different spreading code may be used for different SSBs, e.g., the PBCHDMRS of SSB 1 may be spread with [1 1 1 1], the PBCH DMRS of SSB 2 maybe spread with [1 1 −1 −1], the PBCH DMRS of SSB 3 may be spread with [1−1 1 −1] etc. The value of offset Δ may be implicitly indicated by thespreading code. For example, when Δ=1, the PBCH DMRS of SSB is spreadwith [1 1 1 1], when Δ=2, the PBCH DMRS of SSB is spread with [1 1 −1−1], etc.

Option 5: The value of offset Δ may be indicated by the RMSI PDCCH orRMSI PDSCH. In NR-U, the RMSI CORESET and/or RMSI PDSCH may betransmitted in the same slot associated with the transmitted SSB. Forexample, the RMSI CORESET and SSB may be FDM-ed in the same slot asshown in FIG. 10. A new field may be added to the RMSI PDCCH to carrythe SSB offset value Δ. When a UE detects the SSB, it may decode theRMSI PDCCH that transmitted in the same slot to determine the offsetthat the SSB may be shifted. Therefore, the UE can determine out theframe boundary. A UE may determine the location of the RMSI PDCCH bysome rules pre-defined in the spec or by the RMSI-PDCCH-Config messageconfigured in MIB. The UE may determine PDCCH monitoring occasions fromthe k least significant bits of RMSI-PDCCH-Config. If both M and Oprovided by the k least significant bits of RMSI-PDCCH-Config are equalto 0, the RMSI CORESET may be FDM-ed with SSB in the same slot.

In an alternative embodiment, the RSMI CORESET may be TDM-ed with theSSB in the same slot as shown in FIG. 11. For example, the SSB 0 istransmitted from symbol 4 to symbol 7. The corresponding RMSI CORESETand/or PDSCH may be transmitted from symbol 8 to symbol 9. In thefrequency domain, The RBs used to transmit the RMSI CORESET/PDSCH andthe SSB may be different as shown in the figure; TDM-ed and FDM-ed. Inan alternative embodiment, the same RBs may be used to transmit the RMSICORESET/PDSCH and the SSB.

In yet another embodiment, gNB may perform LBT one beam a time. Forexample, starting from SSB 0, gNB first performs LBT for SSB 0. If SSB 0is transmitted, gNB transmits SSB 0 and performs LBT for next SSB, e.g.,SSB 1. If SSB 0 cannot be transmitted, the remaining SSB burst (SSB 0,SSB 1, SSB 2, SSB 3) is shifted and gNB performs LBT for SSB 0 in nexttime occasion. If SSB 0 is transmitted in time occasion k but SSB 1cannot be transmitted in time occasion k+1. The remaining SSB burst (SSB1, SSB 2, SSB 3) is shifted and gNB performs LBT for SSB 1 in the nexttime occasion (time occasion k+2). This procedure is repeated until allthe SSBs in the burst are transmitted or until the STTC window isexpired.

For initial cell selection for a UE in idle state or inactive state, itis envisaged to assume some fixed STTC, e.g., the UE may assume theduration of the STTC is 5 ms, as pre-defined in the spec. The UE maydetermine the frame boundary based on the pre-defined STTC, detected SSBtransmission offset A, etc.

For a UE in connected state, the UE may be configured with the STTC byone or more of the RRC signaling, MAC CE. The UE may determine the frameboundary based on the SSB index, detected SSB transmission offset Δ etc.An example of the procedure for monitoring and receiving the bundled SSBtransmission is shown in FIG. 12.

SSB Burst Set/Subset Transmission with Opportunistic Transmission

According to another aspect of the application in NR-U, it is envisagedthat SSB transmission may not be bundled, e.g., the gNB may performbeam-based directional LBT for all the beams before the schedule SSBtransmission. For the beams with successful LBT, the corresponding SSBswill be transmitted. For the beams with LBT failure, the gNB may skipthe transmission of corresponding SSBs. This is exemplarily shown inFIG. 13. The gNB performs beam-based directional LBT. It may perform LBTfor all 4 beams before slot 0 of subframe 0. Alternatively, it mayperform LBT for beam 0 and beam 1 before slot 0 of subframe 0. It mayperform LBT for beam 2 and beam 3 before slot 1 of subframe 0. Only LBTfor beam 0 and beam 3 are succeeded. Therefore, only SSB #0 and SSB #3are transmitted at the scheduled location. Meanwhile, SSB #1 and SSB #2are dropped.

Dropping SSB transmission may be critical given its essentiality in NRsystems. To improve reliability of SSB transmission, in addition toscheduled SSB transmission, a UE may be configured with opportunisticSSB transmission to monitor the dropped SSB transmission due to LBTfailure, e.g., SSB #1 and SSB #2 are dropped due to beam-based LBTfailure in the scheduled SSB transmission. Then, the gNB may performbeam-based directional LBT for the dropped SSBs before configuredopportunistic SSB transmission. The corresponding SSBs will betransmitted during the configured opportunistic SSB transmission if thebeam-based LBT is succeeded. The LBT can either be LBT with no backofftime, or LBT with a contention window such as channel access priorityclass 1. The resources may not be used for other transmissionsregardless of the SSB being transmitted in opportunistic SSBtransmission. In so doing, the opportunistic resource may be empty ifthe SSB is not sent. A UE may always assume data is rate matched aroundthe opportunistic resource. Within one opportunistic SSB transmission,multiple SSBs may be transmitted after corresponding LBT successes.Alternatively, opportunistic SSB transmission may be beam specific,e.g., each SSB is configured with dedicated opportunistic SSBtransmission configuration. The opportunistic SSB transmission may beconfigured with one of the following options:

Option 1: A UE may be configured to monitor the opportunistic SSBtransmission within the STTC after the scheduled SSB transmission. Anexample embodiment is shown in FIG. 14. In this example, opportunisticSSB transmission is beam specific and SSB 1 and SSB 2 both fail inscheduled transmission. Successful LBT for SSB 1 is performed at symbol7 in slot 2. SSB1 is transmitted from symbol 8 to symbol 11 inconfigured slot 2. A successful LBT for SSB 2 is performed at symbol 1in slot 3. Then the SSB1 is transmitted from symbol 2 to symbol 5 inslot

In this case, SSB specific offset Δ_(SSB,i) may be introduced to eachSSB from the frame boundary. A UE may determine the frame boundary bythe information of both SSB specific offset Δ_(SSB,i) indicated and theSSB index.

Option 2: A UE may be not configured with STTC. A UE may be configuredto monitor opportunistic SSB transmission occasions between twoscheduled SSB transmissions. An exemplary embodiment is shown in FIG.15. SSB 1 and SSB 2 both fail in the scheduled transmission. A LBT forSSB 1 and SSB 2 is performed at symbol 7 in slot k. Within opportunisticSSB transmission occasion, one shot LBT and a transmission attempt maybe performed. Alternatively, STTC may be configured where multiple LBTand transmission attempts may be performed. If STTC is configured, theSSB offset Δ_(SSB,i) or Δ may be employed by the UE to determine theframe boundary.

Option 3: A UE may be configured with STTC. The UE may be alsoconfigured with opportunistic SSB transmission occasions both two STTCs.An exemplary embodiment is shown in FIG. 16. Within the STTC, if any SSBis not transmitted at the schedule location due to LBT failure, it maybe shifted (e.g., transmit in opportunistic transmission oropportunistic transmission b etc.). Between two STTCs, a UE may beconfigured with SSB transmission occasions, i.e., transmit inopportunistic transmission occasion 1, opportunistic transmissionoccasion 2, etc. The gNB may perform cat 1 or cat 4 LBT before eachopportunistic transmission occasion. If the channel is clear, the gNBwill transmit the SSB within the opportunistic transmission occasion. Ifthe channel is not clear, the gNB will skip the opportunistictransmission occasion. For each opportunistic transmission occasion, thesame SSB may be transmitted, e.g., gNB may do LBT and try to transmitall the 4 SSBs (SSBO, SSB 1, SSB 2, SSB3) in both opportunistictransmission occasion 1 and opportunistic transmission occasion 2. In analternative embodiment, different SSBs may be transmitted in differentopportunistic transmission occasions, e.g., gNB may do LBT and try totransmit SSB 0 and SSB 1 in opportunistic transmission occasion 1. ThegNB may do LBT and attempt transmission of SSB 2 and SSB 3 inopportunistic transmission occasion 2.

According to another embodiment, for initial cell selection, a UE inidle state or inactive state may assume some fixed STTC, e.g., duration,as pre-defined in the spec. The UE may determine the frame boundarybased on the pre-defined STTC, detected SSB transmission offset Δ orΔ_(SSB,i) etc.

For a UE in connected state, the UE may be configured with the STTC byone or more of the RRC signaling and MAC CE. The UE may determine theframe boundary based on the pre-defined/configured STTC, detected SSBtransmission offset Δ or Δ_(SSB,i) etc. An example of the procedure formonitoring and receiving the SSB transmission with opportunistictransmission is shown in FIG. 17.

SSB Transmission with Dedicated STTC

According to yet another aspect of the application, it is envisaged thata UE may be configured to monitor dedicated STTC for each SSB or eachtwo SSBs. An example is shown in FIG. 18.

Within one SSB burst set transmission period (e.g., 20 ms), the STTC maybe configured for each two SSBs transmitted in one slot (instead of thewhole burst or half burst). Assume 15 KHz numerology and 4ms, SSB 0 andSSB 1 may be transmitted in any slot of the 4 slots. Then SSB 2 and SSB3 may slide across the 4 slots within its STTC. The STTCs may becontiguous, e.g., staring from 0 ms, 4ms, 8ms etc. Alternatively, theSTTCs may be non-contiguous, e.g., staring from 0 ms, 5 ms, 1 0ms etc.Within each STTC, the offset Δ of the SSB transmission need to beindicated to the UE for determining the frame boundary.

For initial cell selection, a UE in idle state or inactive state, it mayassume some fixed STTC, e.g., duration and time location, as pre-definedin the spec. The UE may determine the frame boundary based on thepre-defined STTC, SSB transmission offset Δ etc.

For a UE in a connected state, the UE may be configured with the STTC byone or more of the RRC signaling and MAC CE. The UE may determine theframe boundary based on the configured STTC, SSB transmission offset Δetc.

An exemplary procedure for monitoring and receiving the dedicated SSBtransmission with STTC is provided in FIG. 19. The UE may repeat theprocedure for different SSBs in different configured STTC.

SSB Burst Set/Subset Transmission with Flexible Index Order

In yet a further aspect of the application, in NR, the SSB istransmitted on the fixed SSB location, e.g., the SSB #0 is transmittedon SSB location 0, SSB #1 is transmitted on SSB location 1. Therefore,within the SSB transmission, the order of the SSB index is fixed, e.g.,SSB #0, SSB #1, SSB #2, SSB #3.

In NR-U, it is envisaged that a UE may be configured to monitor the SSBtransmission with flexible order index. E.g., SSB index order can bedifferent within the burst. The same SSB may be transmitted on differentSSB locations within the SSB burst set/subset transmission. An exemplaryembodiment is shown in FIG. 20.

The gNB may perform beam-based directional LBT for all the beams beforeslot 0 of subframe 0. If the channel for the scheduled SSB is available,the gNB may transmit the scheduled SSB on the scheduled location, e.g.,the channel is available for SSB1, then the SSB 1 is transmitted on theSSB location 1. If the channel for the scheduled SSB is not availablewhile the channel for the other SSB is available, the gNB may transmitthe available SSB on the that location, e.g., the channel for SSB 0 isnot available while the channel for SSB2 is available, then the SSB 2may be transmitted on the SSB location 0. For the SSBs that have alreadybeen transmitted, the gNB will not perform beam-based LBT for that beamin the rest LBT occasion within one SSB burst set/subset transmission.When multiple un-transmitted SSB channels are available for one SSBlocation, the SSB that has missed its schedule SSB location may havehigher transmission priority. For example, SSB 2 cannot be transmittedon SSB location 2 due to LBT failure. While the channels for SSB 0 andSSB 4 are available. SSB 0 may be transmitted on SSB location 2. If someof the SSBs are not able to be transmitted within the MCOT, gNB may dropthose beams. Alternatively, STTC may be configured and opportunistictransmission may be performed for the failed SSBs.

To determine where the SSB is actually transmitted, a UE may providewith the offset value Δ_(SSB,i) for each SSB. The offset value may benegative. If so, one more bit may be needed to represent whether thevalue is positive or negative.

In an alternative embodiment, the SSB location index information may becarried by the PBCH DMRS and PBCH payload. For example, if there are 64SSBs within the SSB burst set transmission, the PBCH payload bitsā_(Ā+5) , ā_(Ā+6) , ā_(Ā+7) may be the 6th, 5th, and 4th bits of SSBlocation index. The PBCH DMRS may be initialized by the SSB locationindex with

c _(init)=2¹¹(ī _(SSB,location)+1)(└N _(ID) ^(cell)/4┘+1)+2⁶(ī_(SSB,location)30 1)+(N _(ID) ^(cell) mod 4)

ī _(SSB, location) =i _(SSB, location)+4n _(hf)

where,

for L_(max)4, n_(hf) is the number of the half-frame in which the PBCHis transmitted in a frame with n_(h)=0 for the first half-frame in theframe and n_(hf)=1 for the second half-frame in the frame, andi_(SSB,location) is the two least significant bits of the SSB blocklocation index.

for L_(max)=8 or L_(max)=64, n_(hf)=0 and i_(SSB,location) is the threeleast significant bits of the SSB block location index.

In this case, the PBCH payload maybe different for the same SSB index indifferent SSB transmissions. A UE may use the SSB block location indexto determine the frame boundary. Furthermore, if STTC is used to enhancethe SSB transmission, for initial cell selection, a UE in idle state orinactive state may assume some fixed STTC, e.g., duration, aspre-defined in the spec. The UE may determine the frame boundary basedon the pre-defined STTC, detected SSB transmission offset A, SSB blocklocation index etc. For a UE in connected state, the UE may beconfigured with the STTC by one or more of the RRC signaling and MAC CE.The UE may determine the frame boundary based on thepre-defined/configured STTC, detected SSB transmission offset A, SSBlocation index etc. An exemplary embodiment of the procedure formonitoring and receiving the SSB transmission with flexible index orderis illustrated in FIG. 21.

The solutions proposed for indicating the offset Δ may also be appliedhere to indicate the SSB block location index.

Impact on Configurations and Scheduling when DRS/SSB Slides within theSTTC

According to yet even another aspect of the application, when a STTC isused for SSB transmission, the SSB transmission may be shifted in thetiming window. If the SSB transmission is shifted, it may overlap withother configurations or scheduling such as semi-persistent scheduling orPRACH resources. In this scenario, the following options are envisaged:

Option 1: When a UE detects the SSB transmission is shifted, the UE mayassume the other configuration and/or scheduling are not shifted. Anexample of the impact of the SSB shifting on the PRACH resource isexemplary shown in FIGS. 22A-C. These illustrations show scenarios wherethe SSB 0 is transmitted on the schedule location. The timing differencebetween the SSB 0 transmission and the corresponding PRACH resource isdenoted as offset k. FIG. 22B shows the scenario where the SSB 0transmission is shifted by Δ due to the LBT failure at the scheduledlocation. The PRACH resource is not shifted. As a result, the timingdifference between the SSB transmission and corresponding PRACH resourcebecomes k−Δ.

If k−Δ is smaller than the time a UE needs to switch from Dl to UL, theUE may drop the PRACH. A UE may first determine the frame boundary usingthe achieved SSB index and SSB transmission offset A. Then, the UE mayperform PRACH procedure at the configured RACH resource (same location)regardless of whether the SSB transmission shifts. If a UE missed thefirst PRACH resource due to the SSB shifting, it may perform the RACHprocedure at the next available PRACH resource. The same rationale mayalso apply to the paging indication (PI), semi persistent resources,etc. If the SSB overlaps with other transmissions, such as otherreference signals or data due to the shifting, the other transmissionmay be dropped, punctured by the SSB, or rate matched around the SSB.

Option 2: When a UE detects the SSB transmission has shifted, the UE mayassume the other configuration and/or scheduling has shifted,respectively. An exemplary embodiment depicting the impact of SSBshifting on the PRACH resource is shown in FIG. 22C. When the SSB 0transmission is shifted by Δ due to LBT failure at the scheduledlocation, the PRACH resource may be also shifted. For example, the PRACHresource is also shifted by Δ. In so doing, the timing differencebetween the reception of the SSB 0 and PRACH resource is not changed,e.g., still is offset k.

When the PRACH is shifted, it may follow one of the followingalternatives:

Alternative 1: Shifting of the PRACH may be implicitly indicated by theshifting of the SSBs transmission. When a UE determines the SSBtransmission is shifted and determine SSB transmission offset A. The UEmay automatically apply the same offset to the timing location for thePRACH procedure. After a UE determines the configured RACH resourcesthrough the higher-layer parameter PRACHConfigurationlndex, the UE mayperform the PRACH procedure with additional offset rather than theconfigured location. For instance, if the configured PRACH resource islocated at timing t, the UE may transmit message 1 at the location t+Δ.

Alternative 2: Shifting of the PRACH may be explicitly indicated. Forexample, higher-layer parameter PRACHConfigurationOffset may be used toindicate the UE how much offset should be added to the PRACH resourcetiming location. The value of PRACHConfigurationOffset and the value ofthe SSB transmission offset Δ may be same or may be different. Assumethe PRACHConfigurationOffset is set to be A′ and the configured PRACHresource is located at timing t, the UE may transmit the message 1 atthe location t+Δ′.

The same idea may also apply to the paging indication (PI), semipersistent resources, etc. If the SSB is overlapped with othertransmissions such as other reference signals or data due to shifting,the other transmission may be dropped, punctured by the SSB, or ratematched around the SSB.

This solution may work well for the configuration that is FDM-ed withthe SSB. An example is shown in FIG. 23. If the RMSI is FDM-edtransmitted with the SSB, it will respectively shift if the SSB shifts.

According to the present disclosure, it is understood that any or all ofthe systems, methods and processes described herein may be embodied inthe form of computer executable instructions, e.g., program code, storedon a computer-readable storage medium which instructions, when executedby a machine, such as a computer, server, M2M terminal device, M2Mgateway device, transit device or the like, perform and/or implement thesystems, methods and processes described herein. Specifically, any ofthe steps, operations or functions described above may be implemented inthe form of such computer executable instructions. Computer readablestorage media includes volatile and nonvolatile, removable andnon-removable media implemented in any method or technology for storageof information, but such computer readable storage media do not includessignals. Computer readable storage media include, but are not limitedto, RAM, ROM, EEPROM, flash memory or other memory technology, CD ROM,digital versatile disks (DVD) or other optical disk storage, magneticcassettes, magnetic tape, magnetic disk storage or other magneticstorage devices, or any other physical medium which can be used to storethe desired information and which can be accessed by a computer.

According to yet another aspect of the application, a non-transitorycomputer-readable or executable storage medium for storingcomputer-readable or executable instructions is disclosed. The mediummay include one or more computer-executable instructions such asdisclosed above in the plural call flows. The computer executableinstructions may be stored in a memory and executed by a processordisclosed above in FIGS. 1C and 1F, and employed in devices including anode such as for example, end-user equipment.

While the systems and methods have been described in terms of what arepresently considered to be specific aspects, the application need not belimited to the disclosed aspects. It is intended to cover variousmodifications and similar arrangements included within the spirit andscope of the claims, the scope of which should be accorded the broadestinterpretation so as to encompass all such modifications and similarstructures. The present disclosure includes any and all aspects of thefollowing claims.

1. An apparatus comprising: a non-transitory memory includinginstructions stored thereon for monitoring synchronous signals andphysical broadcast channels (SSBs) from a network node; and a processor,operably coupled to the non-transitory memory, configured to execute theinstructions of: configuring the apparatus for an SSB TransmissionTiming Configuration (STTC), where the STTC is a time interval withplural locations accommodating transmission of the SSBs; monitoring theSTTC for the SSBs; and determining a first one of the SSBs in a firstslot of a subframe in a scheduled SSB transmission in the STTC has beentransmitted at a first scheduled location, where the scheduled SSBtransmission of the first one of the SSBs is based upon confirmation ofa successful Listen Before Talk (LBT) available channel prior to thescheduled SSB transmission in the STTC.
 2. The apparatus of claim 1,wherein the processor is further configured to execute the instructionsof determining a second one of the SSBs in the scheduled SSBtransmission in the STTC successfully or failed to transmit at a secondscheduled location.
 3. The apparatus of claim 2, wherein the processoris further configured to execute the instructions of observingtransmission of the second one of the SSBs in the first slot or a secondslot.
 4. The apparatus of claim 1, wherein a time duration of the STTCis configured via RRC signaling.
 5. The apparatus of claim 4, whereinthe network node is configured with an RRC message SSB transmissionTiming duration.
 6. The apparatus of claim 1, wherein the processor isfurther configured to execute the instructions of: receiving an SSBindex of the SSB transmission in the STTC.
 7. The apparatus of claim 6,wherein the SSB index is based upon one or more of a payload of aphysical broadcast channel and a physical broadcast channel demodulationreference signal, and wherein the processor is further configured toexecute the instructions of determining a radio frame boundary basedupon the offset and an SSB block index.
 8. The apparatus of claim 1,wherein the STTC is fixed for initial cell selection for the networknod.
 9. The apparatus of claim 1, wherein the processor is furtherconfigured to execute the instructions of: receiving an offset of theSSB transmission in the STTC.
 10. The apparatus of claim 9, wherein theprocessor is further configured to execute the instructions ofdetermining a radio frame boundary based upon the offset and an SSBblock index.
 11. The apparatus of claim 9, wherein the offset is basedupon a payload of a physical broadcast channel.
 12. The apparatus ofclaim 1, wherein the available channel is in an unlicensed spectrum. 13.An apparatus comprising: a non-transitory memory including instructionsstored thereon for transmitting synchronous signals and physicalbroadcast channels (SSBs); and a processor, operably coupled to thenon-transitory memory, configured to execute the instructions of:performing a Listen Before Talk (LBT) check on a channel; determining,based on the LBT check, availability of the channel, where theavailability is established in a first slot of a subframe prior to ascheduled SSB transmission in an SSB Transmission Timing Configuration(STTC) at a first scheduled location, where the STTC is a time intervalwith plural locations accommodating transmission of the SSBs; andtransmitting a first one of the SSBs in the first slot during thescheduled SSB transmission in the STTC at the first scheduled location.14. The apparatus of claim 13, wherein the processor is furtherconfigured to execute the instructions of determining a successful orfailed transmission of a second one of SSBs in the scheduled SSBtransmission in the STTC at a second scheduled location.
 15. Theapparatus of claim 14, wherein the processor is further configured toexecute the instructions of transmitting the second one of the SSBs inthe first slot or a second slot.
 16. The apparatus of claim 13, whereina time duration of the STTC is configured via RRC signaling.
 17. Theapparatus of claim 16, wherein the apparatus is configured with an RRCmessage SSB transmission Timing duration.
 18. The apparatus of claim 13,wherein the processor is further configured to execute the instructionsof transmitting an SSB index and an offset of the SSB transmission inthe STTC.
 19. The apparatus of claim15, wherein the transmitted secondone of the SSBs in the second slot is based upon a failed LBT availablechannel in the first slot and confirmation of a successful LBT availablechannel in the second slot occurring prior to the transmission of thesecond SSB.
 20. The apparatus of claim 18, wherein the available channelis in an unlicensed spectrum.